Impact of extraction methods on ambient PM2.5 components and cytotoxicity

Obtaining fine particulate matter (PM2.5) samples that are consistent with the natural composition of PM2.5 is crucial for toxicological research. However, current extraction methods inevitably alter the physicochemical properties of PM2.5. Based on variations in processing procedures: extraction solvent (water, ethanol, or dimethyl sulfoxide [DMSO]), sonication, and filtration steps (coarse filtration with 40 μm filters and fine filtration with10 μm filters), five PM2.5 extraction methods were developed, designated as WSF10, ESF10, DSF10, DCF10, and DCSF10, respectively. A mathematical model was developed to evaluate the similarity of PM2.5 samples, and the result showed that PM2.5 extracted by the DCF10 method (DMSO extraction, Coarse filtration, Fine filtration) were closest to that of natural PM2.5, with the highest overall similarity value of 0.70 (0.70 ± 0.01). The cytotoxicity of DCF10-extracted PM2.5 was significantly higher than other groups, inhibiting BEAS-2B cell viability by up to 60% after 9 days of exposure, which aligned best with the similarity results. The outcomes highlight that improper extraction methods may underestimate the actual toxicity of PM2.5. Therefore, optimizing and refining PM2.5 extraction protocols is critical for accurately evaluating its toxicity and providing valid evidence for health risk assessment.